1. A pick-up cartridge, comprising: a cantilever; a stylus mounted on one end of said cantilever; a support member supporting said cantilever at its other end; a substantially square-shaped flexible insulating film base, having a central opening and four band-shaped portions defined between the sides of said insulating film and said central opening, connected to said support member; four band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends and mounted respectively on said four band-shaped portions of said insulating film; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to respective pairs of said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.

3. A pick-up cartridge, comprising: a cantilever; a stylus mounted at one end of said cantilever; a support member supporting said cantilever at its other end; first and second flexible insulating film bases connected to said support member; first and second band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends, parallelly disposed on and supported by said first and second film bases, respectively; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements, said transmitting means comprising a member having first and second projections extending radially therefrom substantially at right angles to each other and in a plane substantially perpendicular to the longitudinal axis of said cantilever, said transmitting means changing the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.

4. A pick-up cartridge, comprising: a cantilever; a stylus mounted on one end of said cantilever; a support member supporting said cantilever at its other end; a substantially square-shaped flexible insulating film base, having a central opening and first and second band-shaped portions defined between the sides of said insulating film base and said central opening, connected to said support member; first and second band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends and mounted substantially perpendicular to each other on said first and second band-shaped portions of said insulating film, respectively; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.

6. A pick-up cartridge, comprising: a cantilever; a stylus mounted on one end of said cantilever; a support member supporting said cantilever at its other end, said support member having first and second strips radially extending therefrom in a V-shaped configuration; a flexible insulating film base mounted on said support member; first and second band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends, disposed on said first and second strips, respectively; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof independently of each other as a function of the transmitted mechanical vibration.

8. A pick-up cartridge, comprising: a cantilever; a stylus mounted on one end of said cantilever; a support member supporting said cantilever at its other end; first and second flexible insulating film bases mounted on said support member in a cross-shaped form; at least two band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends, said piezo-resistive elements being disposed on at least one of two arms of each of said insulating film bases; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.